1. Technical Field
The present invention relates to scroll compressors, and in particular to scroll compressors that have a compression mechanism for compressing a refrigerant and also have an electric motor that serves as a drive source for the compression mechanism. Such scroll compressors may be used as rotary compressors.
2. Description of the Related Art
Japanese Laid-open Patent Publication No. 5-312156 discloses a scroll compressor that may be used as a rotary compressor for air conditioning systems or refrigerators. The known scroll compressor includes a movable scroll that rotates relative to a fixed scroll. As the movable scroll rotates, refrigerant is drawn into and compressed within compression chambers defined between the fixed scroll and the movable scroll, so that the refrigerant is highly pressurized. The compressed refrigerant is then discharged from the compression chambers via a discharge port formed in the fixed scroll.
However, when the refrigerant is being compressed, the pressure of the refrigerant that has been highly compressed within the compression chambers may be applied to both the fixed scroll and the movable scroll. Therefore, the movable scroll may be urged in a direction away from the compression chambers (i.e., away from the fixed scroll) by the highly pressurized refrigerant. Because such force is applied to the movable scroll while the movable scroll is rotating relative to the fixed scroll, a resistance force may be generated against the relative sliding movement between sliding contact portions of the movable scroll and a part of a housing that is disposed on the rear side of the movable scroll. If such a resistance force is relatively large, the compression efficiency of the scroll compressor may be reduced.
Therefore, it is one object of the present teachings to provide improved scroll compressors. For example, in one aspect of the present teachings, scroll compressors are taught that include means for appropriately adjusting or regulating the opposing pressing forces that are applied to the movable scroll, so that resistance against sliding movement can be reduced and compressor efficiency can be increased.
In one of the aspect of the present teachings, scroll compressors are taught that control opposing forces (pressures) that are applied against a movable scroll. By controlling or regulating the opposing forces, resistance to the sliding movement of the movable scroll relative to a fixed scroll and a portion of a compressor housing, which fixed scroll and compressor housing are disposed on opposite sides of the movable scroll, can be appropriately adjusted or regulated.
According to another aspect of the present teachings, scroll compressors may include a movable scroll that is disposed opposite to a fixed scroll. At least one compression chamber may be defined between the fixed scroll and the movable scroll. A motor may drive the movable scroll, so that the movable scroll revolves (orbits) relative to the fixed scroll. As the movable scroll revolves, a refrigerant may be drawn from a suction-side region defined within the compressor into the compression chamber and may be pressurized within the compression chamber. The pressurized refrigerant may then be discharged to a discharge-side region defined within the compressor.
The movable scroll may include a front portion that slidably contacts the fixed scroll. The movable scroll may also include a rear portion that slidably contacts a portion of compressor housing. The pressure of the pressurized refrigerant within the compression chamber may be applied against the front portion of the movable scroll.
The motor is preferably disposed or accommodated within a motor chamber defined within the compressor housing. A first conduct route may serve to communicate discharged refrigerant from the discharge-side region to the motor chamber. The rear surface of the movable scroll may receive pressure that is substantially equal to the pressure within the motor chamber. As a result, the movable scroll may receive pressing forces from both front and rear sides due to the respective pressures within the compression chamber and the motor chamber.
A second conduct route or a controller may serve to adjust or regulate the pressure within the motor chamber, so that the opposing pressing forces applied to the movable scroll may be appropriately adjusted or set. Therefore, the movable scroll may revolve relative to the fixed scroll or the portion of the compressor housing with a minimal or optimal slide resistance.
According to another aspect of the present teachings, the relationship among the pressure (Pm) within the motor chamber (or the pressure of the refrigerant within the motor chamber), the pressure (Ps) within the suction-side region (or the pressure of the suctioned refrigerant), and the pressure (Pd) within the discharge-side region (or the pressure of the discharged refrigerant) may be set as follows: Ps less than Pm less than Pd.
According to another aspect of the present teachings, the controller may include a throttle channel that is defined between the suction-side region and the motor chamber. In this case, the pressure within the motor chamber may be adjusted by permitting refrigerant to flow from the motor chamber into the suction-side region of the compressor. Therefore, the opposing forces applied to the movable scroll may be appropriately balanced. Preferably, the cross sectional area of the throttle channel may be smaller than the cross sectional area of the first conduct route.
According to another aspect of the present teachings, the controller may include a clearance that is defined between the rear surface of the movable scroll and the portion of the compressor housing that faces the rear surface of the movable scroll. In this case, compressed refrigerant within the motor chamber may flow into the suction-side region via the clearance in order to increase the pressure within the suction-side region.
According to another aspect of the present teachings, the controller may include a control valve and the control valve may be disposed within the throttle channel or the second conduct route. In the alternative, the control valve may be disposed within another channel or path that permits the motor chamber to communicate with the suction-side region. In addition, the throttle channel, the clearance and the control valve may be selectively combined to configure the controller.
According to another aspect of the present teachings, methods are taught for balancing opposing forces applied to a movable scroll of a scroll compressor. For example, a first force may be applied against the movable scroll due to the pressure within the motor chamber. The direction of the first force may be opposite to a second force that is applied to the movable scroll due the pressure within the compression chamber. Further, the first force (e.g., the amount of pressure within the motor chamber) may be adjusted or regulated such that the movable scroll revolves with a minimal or optimal resistance between the movable scroll and the fixed scroll and/or the portion of the compressor housing opposite to the movable scroll.
According to another aspect of the present teachings, the step of applying the first force may include communicating discharged refrigerant (compressed refrigerant) from the discharge-side region of the compressor to the motor chamber. According to another aspect of the present teachings, the step of adjusting the first force may include reducing the pressure within the motor chamber. Optionally, the pressure within the motor chamber may be reduced by decreasing the amount of discharged (compressed) refrigerant that is communicated from the discharge side region to the motor chamber. In another optional embodiment of the present teachings, the pressure within the motor chamber may be reduced by relieving the pressure within the compression chamber. In another optional embodiment of the present teachings, the pressure within the motor chamber may be reduced by using a control valve to regulate or control the pressure within the motor chamber.
Additional objects, features and advantages of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims.